In October 1984, it was announced that the Nobel Prize for Physics had been awarded to Carlo Rubbia and Simon van der Meer, for the discovery of the W and Z bosons at the UA1 experiment at CERN just the previous year. This was the capstone discovery in the establishment of the Standard Model of particle physics. The third generation of fermions had already been discovered (the tau lepton by Martin Perl in 1977, the bottom quark by Leon Lederman also in 1977), and the nature of the strong interactions had been elucidated by deep-inelastic scattering experiments at SLAC in the late 1960’s and early 1970’s. Unsuspected by many, particle physics was about to enter an extended period in which no truly surprising experimental results would emerge; subsequent particle experiments have only been able to confirm the Standard Model over and over again, including the eventual discovery of the top quark at Fermilab in 1995. (Astrophysics, of course, has provided substantial evidence for physics beyond the Standard Model, from neutrino oscillations to dark matter and dark energy.)
A month earlier, in September 1984, Michael Green and John Schwarz submitted a paper on anomaly cancellation in superstring theories. String theory had been around for a while, and it had been understood for ten years that it predicted gravity, and was a candidate “theory of everything.” But there were many such candidates, each of which had run into significant difficulties when taken seriously as a theory of quantum gravity. Most people who were paying attention had presumed that string theory would face the same fate, but the Green-Schwarz result convinced them otherwise. A brief article in Physics Today was entitled “Anomaly Cancellation Launches Superstring Bandwagon,” and theorists everywhere jumped to learn everything they could about the exciting new possibilities the theory offered.
So here we are, over twenty years later, still with no surprising new results from particle accelerators (although hopefully that will change soon), and still with strings dominating the landscape (if you will) of theoretical high-energy physics. And still, one hardly needs to mention, with no clear path to connecting string theory to low-energy phenomenology, nor indeed any likely experimental tests of any sort.
In the circumstances, it’s not surprising there would be something of a backlash against string theory. The latest manifestation of anti-stringy sentiment is in two new books aimed at popular audiences: Peter Woit‘s Not Even Wrong: The Failure of String Theory and the Continuing Challenge to Unify the Laws of Physics, and Lee Smolin’s The Trouble With Physics: The Rise of String Theory, The Fall of a Science, and What Comes Next. I haven’t read either book, so I won’t presume to review them, but I think we’ve heard the core arguments expressed on this blog and elsewhere. I’m a firm believer that it’s good to have such books out there; I’m happy to let the public in on our internecine squabbles, just as I’m happy to keep them updated on tentative experimental results and speculative theoretical ideas. It seems unduly patronizing to think that we can’t reveal anything to the wider world until everyone in the community agrees on it.
But I don’t actually agree with what the books are saying. Here is the main point I want to make with this post, trite though it may be: the reason why string theory is so popular in physics departments is because, in the considered judgment of a large number of smart people, it is the most promising route to quantizing gravity and moving physics beyond the Standard Model. I don’t necessarily want to rehash the reasons why people think string theory is promising — I’m not positing an objective measurement of the relative merits, but simply an empirical observation about people’s best judgments. Rather, I just want to emphasize that, when you get right down to it, people like string theory for intellectual reasons, not socio-psycho-political ones. It’s not a Vast String Theory Conspiracy, funded by shadowy billionaires who funnel money through Princeton and Santa Barbara to brainwash naive onlookers into believing the hype. It’s trained experts who think that this is the best way to go, based on the results they have seen thus far. And — here’s the punchline — such judgments could change, if new results (experimental or theoretical) came along to suggest that there were some better idea. The way to garner support for alternative approaches is not to complain about the dominance of string theory; it’s to make the substantive case that some specific alternative is more promising. (Which people are certainly trying to do, in addition to the socio-psycho-political commentating about which I am kvetching.)
That is, after all, the way string theory itself became popular. Green and Schwarz labored for years on a relatively lonely quest to understand the theory, before they were able to demonstrate anomaly cancellation. This one result got people psyched about the theory, and off it went. It’s not a matter of impressionable young physicists docilely obeying the dictates of their elders. Read Jacques Distler’s (absolutely typical) story about how he dived into string theory as a graduate student, despite the fact that his advisor Sidney Coleman wasn’t working on it. In a completely different field, listen to Nobel-winning economist Gary Becker on the response to his ideas (via Marginal Revolution):
“There was a sea change. I began to notice it in the 1970s and 1980s. A lot of the younger people coming out of Harvard, MIT and Stanford were very interested in what I was doing, even though their faculty were mainly – not entirely – opposed to the sort of stuff I was doing.”
This is just how academics act. They are stubborn and willful (even at a charmingly young age!), and ultimately more persuaded by ideas than by hectoring from their elders. And it’s not just the charmingly young — if good ideas come along, supported by exciting results, plenty of entrenched middle-aged fogeys like myself will be happy to join the party. If you build it, they will come.
There’s no question that academic fields are heavily influenced by fads and bandwagons, and physics is no exception. But there are also built-in mechanisms that work to protect a certain amount of diversity of ideas — tenure, of course, but also the basic decentralized nature of university hiring, in which different departments will be interested in varying degrees in hiring people in certain fields. Since the nature of science is that we don’t yet know the right answers to the questions we are currently asking, different people will have incompatible intuitions about what avenues are the most promising to pursue. Some people are impressed by finite scattering amplitudes, others like covariant-looking formulations, others don’t want to stray too far from the data. The thing is, these considered judgments are the best guide we have, even if they are not always right. Green and Schwarz were lonely, but they persevered. If you want to duplicate their success, find a surprising new result! You can’t ask a department to hire people in an area they don’t think is promising, just because it serves the greater goal of diversifying the field overall. Crypto-socialist pinko though I may be in the political arena, when it comes to intellectual life I’m a firm believer in the free market of ideas, and would tend to resist affirmative-action programs for underrepresented theories.
The bandwagons come and go, influenced by both data and new ideas. When I was in grad school in 1990, things were in a lull in fundamental physics generally, and students were escaping to Wall Street and elsewhere. The discovery by COBE of temperature anisotropies in the microwave background re-invigorated cosmology, and attracted a number of bright young theorists. The Second Superstring Revolution in the mid-90’s did the same for string theory. There’s every reason to believe that the LHC will do the same for phenomenology — the leading indicators are already easily visible.
The thing that has kept string theory alive is that interesting results have kept coming, from the 70’s (gravity!), to the 80’s (anomaly cancellation, five critical string theories), to the 90’s (branes, dualities, black hole entropy, AdS/CFT). The last few years haven’t witnessed their own “revolution” (unless you count the landscape), but it would seem a little impatient to give up on that basis alone. If nothing else, string theory is extraordinarily fruitful and robust. Indeed, the AdS/CFT correspondence says you can’t really separate field theory and string theory. Take an ordinary gauge theory in flat four-dimensional spacetime, and make it as supersymmetric as possible without adding gravity. Then make the coupling very strong, and the degrees of freedom rearrange themselves — just as the strong coupling in QCD makes the quarks and gluons rearrange themselves into pions and nucleons — into Type IIB superstrings living in a ten-dimensional spacetime. How amazing is that? It’s not proof that strings are connected to the real world (which, as people sometimes forget, is not manifestly maximally supersymmetric, and does in fact involve gravity), but it’s the kind of rich structure that keeps people optimistic that string theory is on the right track.
Of course, you do have to make the case that your personally favorite approach is a promising one, to the public and to colleagues in other specialties as well as to graduate students. This is not always a job that string theorists have done well. Some of them, I’ve heard rumors, can even occasionally be a mite arrogant. Let’s admit, this is something of an occupational hazard among academics; if universities fired all the arrogant people, the remaining faculty would be stuck teaching twenty courses a semester. And, while I think that an enormous landscape of stringy vacua might very well exist, I think that supporters of the idea have dramatically failed to take seriously the difficulty of actually calculating anything on that basis. Discussions about these crucial issues have all too often degenerated into sophomore-level philosophy-of-science debates, which haven’t done credit to either side. The truth is, we’re not doing science in a new way, it’s the same old way — trying to come up with the simplest possible consistent and coherent framework that explains the phenomena we observe.
And (to add one more “of course”), needless to say we need to keep our eyes on the prize, which really is explaining those phenomena. Sometimes people do get entranced with the math, which is fine, but as physicists the ultimate arbiter of interestingness is a connection to data. String theory hasn’t done that yet, and might not do it for a long while, but in the end will have to, one way or another. It’s hard! But string theory will either progress to the point where its connections to reality become increasingly manifest and specific, or people will lose interest and work on other things. That’s the way the system works.
Update: Interesting reports from the Strings 2006 meeting in Beijing from Victor Rivelles, Jonathan Shock, and Dennis Overbye.
Dear Yidun,
You said:
I absolutely agree that society needs to hear from the full range of scientific thought. I don’t find anything at all uncomfortable about popular books about alternatives to string theory. It’s just the notion of popular books that seem to be (in large part) about string theory but against it that seems weird to me somehow.
If popularizations of string theory often misrepresented the status of the theory by saying “These ideas are definitely true” then I’d be more sympathetic. But my experience has been that string theorists almost always use the standard tentative language of science when presenting their work to the public. Their sin (and mine, I’ll freely admit) seems to be simply that while saying “we don’t know if this is true”, we’re still smiling and have an eager, excited light in our eyes. Maybe we should be even more forceful about the lack of experimental evidence, but we’re certainly not distorting our own level of hope and enthusiasm.
For those who want to counter string theory’s “hype”, I feel like the best bet would be to dilute it, not to fight it head on. Get the public excited about other approaches to quantum gravity directly! Why spend lots of time arguing that string theory isn’t the right approach when you could spend that time explaining why something else is?
Agreed. I think that I and string theorists in general welcome that criticism. So if anyone out there has a no-go theorem for string theory or new arguments about why it isn’t worth spending time on, I hope that they get them peer reviewed and published as soon as possible. Thus far, though, it seems like most string theorists (from old experts to young folks like me) haven’t been scientifically convinced to give up on the field yet.
Steuard,
The problem with string theory isn’t the lack of experimental evidence, it’s the lack of any predictions about any experiments, and, worse than that, the lack of any plausible idea of how one is ever going to get such a prediction, despite more than 20 years of trying. In my experience, string theorists very rarely publicly acknowledge this situation, or explain what the source of these problems is.
” the notion of popular books that seem to be (in large part) about string theory but against it that seems weird to me somehow”
Given that there are serious problems with making string theory unification work that are well-known to the experts whose existence is being ignored by those hyping string theory to the public, what should one do about this? A referee would properly reject a submitted technical paper about this on the grounds that these problems are known to the experts, so such a paper would not be a scientific criticism. But non-experts with an interest in the subject deserve an explanation of the problems. What should one do in this circumstance? Perhaps write a detailed serious book in which a couple chapters out of 19 would be devoted to laying these things out clearly?
I strongly disagree with your idea that the answer to overhyping string theory is to overhype other ideas. The respect that the public has for science is based on the fact that scientists have been able to sort out what is true about the world and what isn’t. If we decide that upholding standard scientific norms about this is less important than generating enthusiasm for what we do, we will ultimately destroy our credibility and turn science into science fiction, a subject which lots of people are enthusiastic about, but is very different indeed.
Dear Santo D’Agostino,
I asked what string detractors felt string theorists should do differently, and you replied:
The thing is, I feel like we already do all that, at least within reason. As I indicated before, you can’t expect us to have a disclaimer on every single slide of our talks. And a talk about the painstaking process of science simply won’t capture the public imagination the way that a talk about a single cool idea can. The challenge is to find a way of talking about cool ideas while still giving an accurate picture of the status of the science along the way. (Reel them in with exciting ideas, and slip in as much training in the scientific method as you can.) It’s not that hard: the search for fruitful ideas can be pretty cool itself. But not, in my opinion, cool enough to carry a whole public lecture.
But that’s a challenge for all scientists, not just string theorists, and I’m not convinced that string theorists are particularly worse at conveying their understanding of the tentativeness of their ideas than the others. The main difference that I see between string theory and other fields in this respect is that there is a notable community of other physicists who seem to think that the string theorists’ judgement of the status of their own work is incorrect.
Unfortunately, I have no clear idea how that disparity arose, or what to do about it. But I am not willing to believe that it’s the result of greedy string theorists trying to pump up their funding by misrepresenting the progress of their field: that is entirely inconsistent with my experience. And I’m awfully hesitant to believe that it’s because string theorists are engaging in groupthink (or that they fear unemployment if they speak out against the field). As others have said, there are plenty of other cool subjects in physics available for anyone who thinks string theory is off base (some of which would be quite easy to shift to gradually). It’s hard for me to believe that a substantial number of people feel “trapped” into supporting string theory.
Steuard,
Everyone is trapped into supporting string theory if they want to get published, or even on arxiv. If you get suppressed for having an “alternative to currently accepted [string] theory” (Stanley Brown, PRL editor, in email to me), that’s equivalent to be trapped into supporting string theory.
When you point out that there isn’t a proper theory there at all unlike your work, they give you an abusive rant about their personal problems in life or whatever, and when you point out they are just bitter, you just get get them saying the same thing back to you. They just act like kids and hurl abuse. You can’t answer back, or they say you are being censored for being rude.
Dear Steuard,
Thanks for your reply!
The fact is that I haven’t really seen any physicist or mathematician who is totally against string theory, I mean the theory per se, or against anyone who does the theory. They are just trying their best to criticize objectively the shortcomings of the theory based on their understanding, though they might not be completely right. None of them is persuading people from doing the theory. Physicists outside the field and the general public need both positive and negative views on the theory before it is shown precisely to be correct. Moreover, almost no string theorist would like to do so, we thus need other people to do it.
I am doing loop quantum gravity, I would not feel any uncomfortable on any rational criticism on LQG. And I think that there have been many such criticisms already. However, in contrast to those who criticize string theory, there exist at least several string theorists who extremely dislike any other alternative to quantum gravity; not only in their minds but also in their writing to the public, ST is the only way (Do you really think this is physically right at the moment?)and all others are definitely wrong that are worth no concern. I don’t want to come back to this point anymore, since I don’t really care.
I do think people doing either ST or LQG, or any other approach should work hard to improve their own work and advertise their own work. At least in my case, I will try my best. You should have seen that apart from arguing the necesity of criticism I didn’t say anything against ST or any other. I’ve taken string courses, attended string summer schools and read interesting string papers , because I think keeping my mind open will never be bad. My supervisor is also happy with this, since he is such a prominent open-minded physicist.
By the way, I have read your nice website and is fascinated by your intriguing introductory lecture to ST. I am actually inspired by it to make one for LQG and put it on my blog in the near future.
Thanks,
Y.
Dear Peter,
I asked, “Why do we need popular science books dedicated (or half-dedicated) not to sharing some exciting new idea but rather to cutting one down?” You replied:
Rather than spending time defending my use of the word “new”, I’ll go ahead and retract it. But the central point of my question still stands: What is the goal of a popular science book (half-)dedicated to debunking a theory (rather than simply building excitement for alternate ideas as well)? Is the fear simply that broad public interest in string theory is “corrupting the youth” (so the next generation of physicists will only want to do strings)?
Perhaps so; periodic evaluation of scientific programs is a good thing. But that sounds like the sort of thing to discuss in a review article, or at a major scientific conference, or in NSF policy forums. It’s not entirely clear to me how a book aimed at the general public is the best place for it.
I do understand your point that there should be some sort of correction if the public has mistakenly gotten the impression that string theory is established scientific “fact” or that there are no major outstanding problems with it. But do they actually have that impression? Or do they just think that string theory is a nifty idea if it turns out to be true?
Could you be a little more clear about what you mean by “overhyped”? How would you distinguish “overhyping” from “standard public outreach”? Who (specifically) is doing the overhyping? It sounds like you feel that string theorists should be doing something differently, but I don’t see that you’ve addressed the questions about that from my original post. Like any good scientists, we’re going to share our excitement about our work with the public, and I have yet to see a popular presentation of string theory that doesn’t acknowledge that it has no immediate path to make contact with experiment.
What I’d really like are some specifics. What do you want me as a string theorist to do differently? I already tell people that we have no idea how to test string theory (yet), and that we might be a little nuts for even attempting this sort of unification today. I tell them in no uncertain terms that the theory could easily still fall flat on its face. But I (like most string theorists) remain cautiously optimistic about its long-term chances, and I make no secret of that (nor of my excitement for the field). Given that I have not (yet) accepted your scientific criticisms of the theory as spelling doom for the field, how would you like to see my approach change?
That’s a bit below the belt, isn’t it?
Perhaps related to my previously stated confusion about your term “overhype”, it sounds like you and I have a fundamental difference of opinion as to the proper way for scientists to communicate with the general public. My own hope is that by encouraging a broader public interest in science, public understanding of science (both its potential and its limitations) will increase as well. To make that happen, I feel that we must replace the broad perception that “science is hard and boring” with something closer to “science is exciting (and maybe even risky)”.
On the other hand, my impression is that you would argue that the public perception of science will suffer if scientists publicize too many ideas that are still tentative. As you said,
I conclude that you would say that scientists should limit their public statements to what we’re pretty sure is “truth” to avoid eroding public confidence in our work entirely.
If that is an accurate understanding of your point, then I should start by saying that I do sympathize with your concern. There’s already been erosion of public confidence of this sort in areas like nutrition. (“Oh, so this week science says eggs are good for you? I don’t buy it: they’ll just flip flop again next month.”) But I don’t think that we can avoid the problem by tightening our standards on public statements indefinitely: the more our reputation rests on “we make no mistakes”, the harder we’ll fall when we inevitably fail to meet that standard.
Better, to my mind, is doing our best to help the public understand how science actually works and to teach them to be discerning consumers of scientific information. I don’t see how to do that if we focus our outreach primarily on firmly established results. The only approach that I can see being effective is to discuss the full range of ideas, from well-established core principles through tentatively established theories and all the way out to speculative new proposals. And that has the side benefit of allowing us to talk at least a bit about the things that we find most exciting.
Alejandro#61:
Assuming that QFT is not fundamental, you can also argue that many of the arguments for string theory are not valid arguments at all. If you think of QFT as the low energy remnant of some fundamental theory then you naturally end up with some renormalizable theory. Renormalizability is linked to various symmetries. So, we cannot use our intuitions gained from experience in dealing with QFT and extrapolate that to write down the fundamental theory.
The lesson from history is that it is best to focus on things that are problematic for the known physics. But extrapolating familiar concepts to ”fix” these problems often leads to the wrong solutions, like e.g. the Aether in the 19-th century.
Doug (not the Doug above) writes:
This comment cuts to the heart of quantum mechanics, the assumption of splitting to a Hilbert space. I think that the way to address it is with Schwinger’s measurement algebra. See, for example, LP Horwitz, 1997 hep-th/9702080
Another way of putting this is to note that it is possible to define QM completely from a formalism based on density matrices. One can make all the calculations one could need by using density matrices only, with no references to spinors. But one can then produce the spinors by pretending a special density matrix exists, call it |0> == |a>
Science: “entanglement philosophy”, as you call it, has provable macroscopic consequences such as mathematically secure cryptography and the existence of an efficient factorization algorithm. In your comment, you seem to want to deny the objective existence of entanglement (you call it “metaphysical”), but the fact that it is a well-defined and in some cases (i.e., two-qubit entanglement) quantifyable concept with unique observable (computational) consequences refutes this perspective.
Second, you seem to think that entanglement implies a violation of causality. However, if by causality you mean signalling faster than the speed of light this is not the case. Entanglement cannot be used to signal faster than light because of the no-cloning theorem: an unknown quantum state cannot be copied perfectly. In fact, non-relativistic quantum theory fits very tightly with a maximum signalling speed, due to its probabilistic nature.
Third, when you talk about the Dirac sea, you seem to think that the uncertainty arises due to imperfect knowledge of the system (Brownian motion is a classical phenomenon). This is called a hidden variable theory, and was explicitly ruled out by Bell’s formulation of his famous inequaliies.
Finally, the uncertainty principle is a statement about the fundamental accuracy with which two non-commuting observables can be measured. The two observables corresponding to linear and circular polarization do not commute, and therefore define an uncertainty relation. Your argument that this does not apply to photons because they do not exist after detection is not correct: In principle there exist so-called Quantum Non-Demolition measurements that do not destroy the photon (sorry, no Wikipedia link available). Using such QND detectors, the statistics of the uncertainty relation constructed above can be retrieved. A QND measurement of a microwave photon was demonstrated experimentally by Haroche’s group in Paris in 1990. My point is that the uncertainty principle is part of the Hilbert space structure of quantum mechanics, and applies to everything.
For some reason the link to hidden variable theories and Bell inequalities was broken in my previous comment.
Quantum gravity is a hard problem. All of the approaches to it at the moment are speculative. At the same time, bright young physicists are told that their purpose in life is to solve the problem of quantum gravity; that’s where the glory is. So a large number of young physicists want to try to work on quantum gravity when they get to the graduate level. The university system requires that a graduate student be able to make concrete progress on a well-defined problem which can be verified by the faculty and outside reviewers.
String theory is so vast that, for the foreseeable future, there will be areas where small amounts of progress – suitable for a PhD thesis – will be possible. I have no doubt that a large part of string theory’s success in achieving dominance is due to its compatibility with the university system. It may be that progress in some other area – for example, the foundations of quantum mechanics – is what will be needed to have a breakthrough in quantum gravity, but you can’t advise graduate students to work on that, because they will think very hard for five years and have nothing to show for it at the end, except perhaps a religious dedication to their favorite interpretation of quantum mechanics.
Sean makes the point that those who allocate funding and jobs are intelligent people, capable of making their own decisions based on their understanding of how promising each research area is. This is largely true, and it would obviously be a mistake to impose anything like “affirmative action” for alternative research projects. However, there is still a legitimate question of whether the people allocating resources or jobs are vulnerable to groupthink. No doubt the knee-jerk reaction of many physicists will be to insist that physicists are immune to groupthink, due to their perfect minds. But recall that a person who is completely rational will give some weight to the consensus of the group, and will sometimes go along with the group’s perception rather than his own. This means that groupthink can cause even perfectly rational individuals to collectively make a mistake which none of them would have made on their own.
The question is whether groupthink is in any way responsible for the current situation. Look specifically at the statement that string theory is, by far, the best hope for a theory of quantum gravity. Obviously, deciding which approach is the best hope is a judgment call, and we will usually defer to the experts on this. The question is *not* whether the statement “string theory is the approach most likely to succeed in producing a usable theory of quantum gravity” is true. The question is whether the perception of its truth is influenced by acquiescence to the better judgment of the group. String theory can be completely true, and it may still be the case that its dominance is helped by groupthink.
Another question is whether there is a community of string theorists at all, with a common interest in furthering “the cause” of string theory. Furthering the cause may mean promoting public perception of string theory, trying to influence political decision-makers, or trying explicitly to ensure that jobs preferentially go to those who are supportive of the string theory cause, and to deny jobs, credibility or attention to those who criticize the theory. Furthering the cause does not mean researching string theory, but rather trying to improve the support that string theory receives from universities, the public and the government. I think it is unnecessary for me to point to specific individuals or actions to make the case that there is a string theory community in precisely this sense.
Given that there is such a community, then there is a conflict of interest whenever a member of the string theory community is asked to allocate resources on behalf of their physics department. They have two loyalties – to the physics department and to the string theory cause. Now, it will be insisted that this conflict of interest causes no problems – that string theorists are perfectly capable of putting aside their dedication to the cause when it comes to departmental business. The astute individual will observe that everybody who has a conflict of interest says the same thing.
A more sober objection would be that astronomers, condensed-matter physicists and so on are in exactly the same situation, and that it is unfair to single out string theorists in this regard. However, there is a difference. String theory is different because it is a conjecture. Condensed matter physicists may work on particular conjectures, but different ones will work on different conjectures. String theorists, on the other hand, all work on the same conjecture (or pretty much – you might count braneworld as a different conjecture, but it isn’t really so different). What binds them together as a community is that they all devote their time and effort to considering the consequences of the string conjecture being true. This is a situation ripe for fostering groupthink. (Recall that even individuals who behave completely rationally will fall prey to groupthink; being clever does not make you immune.) If you wanted to make groupthink more likely, you would get the string theorists to talk mostly to each other, and to consider themselves more intelligent than non-string theorists. This is already the case – string theorists only talk to other string theorists, and they consider themselves more intelligent than non-string theorists (like you, Sean).
Is that what they’re told nowadays?
Back when I was in graduate school (as related in the post Sean linked to above), I was told, quite firmly, that thinking about quantum gravity was an utter waste of time.
The string theorists I know talk seriously to a broad range of people, from nuclear physicists to number theorists (see the posts I linked to above).
As to whether they think themselves smarter than their interlocutors, that’s the prerogative of youth, isn’t it? Not to worry, even if they do, that misapprehension will quickly fade.
Jaques Distler Wrote:
Hi Jaques. Of course they apply broadly to investments in general well beyond research. I’m surprised and sorry that didn’t come through more clearly.
I suppose if you don’t see String theorists as behaving markedly differently from other researchers, it doesn’t make sense why String theory would be singled out. Is it possible that the community doesn’t see itself as behaving unusually for a scientific discipline? I guess I never even considered the idea that the community sees itself as open and welcoming to outsiders, critics and new ideas from outside. If that is the case, we could clear up a lot of confusion because the (false?)impression many outsiders have is that leaders in the string community generally believe only the community can evaluate the community.
Having recently spent part of a week at Perimeter as an outsider outsider, I simply didn’t think of admonishing other research groups like LQG to be more self-critical or open to outside judgment. At least in my case, they really reached out in terms of self-critique and seemed to have the hang of the research diversification issue down cold. In fact, my input was solicited much more than I had something informed to contribute as I was invited there to lecture on Economics and Gauge theory. If I ever run across a single String research group out there which is comparably adventurous and open to outsiders with new ideas, I can assure you I will hold them up as a model.
Eric
Steuard #102:
If popularizations of string theory often misrepresented the status of the theory by saying “These ideas are definitely true” then I’d be more sympathetic. But my experience has been that string theorists almost always use the standard tentative language of science when presenting their work to the public. Their sin (and mine, I’ll freely admit) seems to be simply that while saying “we don’t know if this is true”, we’re still smiling and have an eager, excited light in our eyes.
While you don’t hear much string theory hype from serious people these days, the string theory bandwagon was largely created by Witten’s massive marketing between the two string revolutions (“Theory of everything”. “Magic and mystery”. “21st century mathematics which by chance landed in the 20th century”. “Every advanced civilation discovers QM, GR, SUSY, and eventually string theory”. “Good wrong ideas are very scarce, and no idea as magnificent as string theory has ever been wrong”.) Just look in John Horgan’s book, where EW implies that not believing in string theory is like thinking that the sky has pink polka dots on it. Positively Lubosian.
Witten’s hype seemed to stop around 1998, though. By coincidence, this is also the year that the CC was found to be positive, something that EW described as the most disturbing fact he had ever learned. I think that the problem is not so much the 120 or 63 orders of magnitude, but rather the sign – it is difficult to use holographic ideas since de Sitter space lacks the right kind of asymptopia to put holographic data on. Perhaps most revealing was his comment from the floor during Strings 2005, where he said something like QM was murky in dS space.
Also, after 20 years Witten now seems to have stopped claiming that string theory makes one prediction, SUSY (and one postdiction, gravity), perhaps because the Tevatron should have seen something weird in their dataset by now, had SUSY been there in the first place.
Part of the effect of string theory’s success has been to change people’s minds about that to some extent. It’s now possible to have a career studying quantum gravity, as we can all see from the many examples of string theorists with tenure and on tenure-tracks. If it wasn’t for strings, perhaps those alternatives would have even less support than they do now; maybe they should be thanking you.
That’s a good start. Perhaps if they can convince their colleagues to do the same then the other physicists in the physics departments will stop commenting to each other about how arrogant and narcissistic the string theorists are. I believe there have been blog entries here at cosmicvariance.com on the subject; I’m quite sure that this isn’t a figment of my imagination.
They think they are smarter than the people who *aren’t* their interlocutors. Of course, they will discover by experience that they are no smarter, on average, than the people in the physics department who they talk to. But these are kids who have been doing well in exams their whole life, always top of the class. Their self-respect is derived, to a large extent, from their perception of themselves as intelligent, because this is what has set them apart from their peers and brought them success in life. Now they are members of a group, a group of people famed for being intelligent. But they are no longer the smartest person around. Suddenly their intelligence is average. Self-respect is no longer based on how much more intelligent they are than their peers; it is based on how much more intelligent their group is compared to everybody else.
By the way, I hear you’re a string theorist. “You must be very intelligent.” Even the nuclear physicists will say it. Probably not the number theorists, though. They’re not impressed by that.
Prof Carroll,
“But I think both of you are overestimating the “stickiness” of one’s research specialty. String theorists are not created in specially-designed pods in the basement laboratories of other string theorists. They are just physicists who look at what is going on and decide that string theory is the most interesting thing to work on. (So it is not really like a monopoly — try as you might, you won’t convince the Microsoft corporation to switch to selling Apple software.) If you don’t agree, convince them otherwise! Get an exciting physics result that persuades people who are now working on string theory that they should switch to something else. That is the only way to ultimately make progress.”
This would be true if students are hired without regard or bias to their possible, likely choice of research areas. In my experience, students are not hired in such fashion. A department where high energy physics is dominated by string theorists (e.g Princeton in the 90’s) will hire grad students who may already be inclined to study string theory, and most of these hired students will eventually study string theory if only because the string theorists can pay them. Ultimately, the funding allocations determine the number of people graduating in a field. So I think the concern about allocation of resources is justified even in relation to individual departmental hiring. If a critical mass of people are trained in a discipline and invest years of effort into research, it is reasonable to believe that they would be subject to groupthink, if only because they are human, and would be unwilling to be particularly objective about their area of work. It is a myth that physicists (or any type of scientists) make objective judgements independent of their personal investments of time and labor.
Steuard,
I am not a high energy physicist, and I tend to agree with some that String theory is more visible in the lay media than most other fields of physics, at least judging from the number of articles in the NYT. I think that this may be of concern to the string community itself in the intermediate run. The public is a fickle beast which can turn hostile if not kept fed regularly. Personally, from what little I have studied of string theory, I can understand its attraction to a theorist.
Steuart,
No, I don’t think that pointing out that you’re publicly attacking a book you haven’t read, seemingly just because you’ve heard it contains sections critical of a research program you support is “below the belt”.
If you want specific examples of hype I’m talking about, go to my blog, type “hype” in the search engine.
I’m all in favor of people writing books for children or adults who know nothing about science designed to try and get them interested in the subject, but that’s just not the kind of book I wrote, and it’s not the only kind of “popular” science book. Personally, when I want to learn more about some area of science I’m not expert in, the last thing I want to spend my time reading is some breathless, hype-filled promotional piece full of wishful thinking about how exciting and wonderful the author’s research program is. I’d much rather read an intellectually serious book, full of accurate information carefully explained. The people who read expository “popular” books about science are not largely uninformed people who need to be convinced that science is interesting and worth doing. They’re often highly scientifically literate, and trying to learn more about a topic they’re already interested in. When I was writing I was trying to write something I would actually want to read if I knew less about the subject in question. After I was done, my main worry was that I had written something that was so arcane no one would want to read it. I’ve been very gratified to see that that doesn’t seem to be a problem.
Recall that this book was originally slated to be published by a university press, before two string theorists exerted their influence to put a stop to that. I’ve never heard of these “NSF policy forums” where the state of string theory research is evaluated, but would be glad to speak at one. I’d also be glad to speak at Strings 200X about the problems of string theory, but this doesn’t seem to be topic the organizers of that conference series are looking for people to speak about.
What should string theorists do? First, there’s a list of things they should stop doing: hyping ideas that haven’t worked, attacking anyone who criticizes them as a crackpot, censoring criticism, engaging in anthropic pseudo-science. More positively, instead of trying to suppress serious discussion of the problems facing the field, they should be encouraging it, and trying to understand exactly what the obstructions to progress on the string theory unification program are, and why attempts to get around them have all so far failed.
Science: Bell showed that in local hidden variable theories we can derive Bell inequalities (which are violated in experiment). Bohmian mechanics assumes nonlocal hidden variables, and it is not ruled out by Bell’s theorem: You cannot (correctly) derive a Bell inequality in Bohmian mechanics.
I am disappointed that you do not respond to my arguments concerning the “reality” of quantum entanglement in a scientific manner.
Eric wrote:
Did you … umh … talk to the string theorists at Perimeter?
Were they unadventurous and hostile to outsiders with new ideas?
How about the string theorists at other places you’ve visited?
“Part Time” wrote:
I see.
Yet another pernicious effect of string theory.
Hi Prof. Distler,
For what it’s worth, I think it’s great that you are prepared to engage in discussion on this topic; it will help to dispel a certain perception of string theorists in some quarters.
A few questions. (1) For a young person whose general interests lean toward formal particle theory, one consideration when choosing a research topic could be the following: There are already lots of people working on string theory/branes, some of them very smart. So the chances for a new person entering that field to make an impact and come up with something genuinely significant might not be that great. On the other hand, with all the attention on string theory, perhaps there are other topics which have not been getting the attention they deserve, and where there is good potential for making interesting and worthwhile progress. What would be your advice to someone who was thinking of working on a non-string topic after making considerations along these lines? (This might depend on your view of the particular topic. Presumably there’s no need to try to convince you of the existence of other interesting formal theory topics besides string theory, since you have already studied one such topic yourself in hep-th/9305026. For the sake of argument, let’s assume that the non-string topic the person was considering working on was equally interesting to the topic you studied there.)
(2) How do you think such a person would fare in later job applications to formal particle theory groups? It looks like most of such groups are focussing on string theory, branes etc. Would they be at all interested in applications from people working on other formal theory topics? (In case the progress that the person in question had made on their chosen topic is relevant here, let’s assume for the sake of argument that their results were enough for them to easily win a prestigeous postdoc fellowship in open competition, e.g. a Marie Curie fellowship from the EU.)
sorry, hep-th/9305026 should have been hep-lat/9305026 in the preceding comment.
As anticipated by some of the off-topic commenters, I deleted some of the off-topic comments (although perhaps not as many as I should have). Yeah, I know, censorship of non-mainstream ideas, Einstein never would have been recognized today, etc.
Well, first of all, let’s be realistic and acknowledge that, in coming years, the emphasis in hiring is going to be heavily tipped towards phenomenology and cosmology. People doing formal stuff (string-related or not) are going to have a harder time getting jobs.
My advice to all graduate students is try to work on a variety of different topics. When you’re a postdoc (and have to start applying for new jobs within 15 months of arriving at your current one), it’s a lot harder to “retool” in a significant way. If you cultivated a diverse background as a graduate student, you’ll have a much easier time.
Mike Peskin went further and used to (?) require that all his students who wanted to work on string theory publish a phenomenology paper first.
The second thing I’d say is that shying away from a subject because it happens to be popular is not necessarily a good strategy. The whole thrust of Sean’s post is that high energy theorists tend to be a restless lot, descending on a “hot” topic, where progress can be made quickly, and then abandoning it for the next “hot” topic when progress slows.
As a graduate student, just starting out, you’re probably a little slower to gear up, so I’d stay away from the really high-traffic lanes. But any topic worth thinking about (stringy or not) already has (or has had) smart people thinking about it. There’s no way to avoid competition, unless you want to spend your time thinking about topics so obscure or intractable that they probably aren’t worth thinking about.
Besides, if you want your results to be noticed, it would probably help if there are some other people interested in the topic.
Thinking about QCD at finite temperatures and densities is a very interesting (and, because of RHIC, relevant) subject. On my blog, I’ve emphasized the AdS/CFT approaches, but there is a lot of interesting other work that would appeal to someone formally-inclined.
There’s a host of topics on the interface between mathematics and quantum field theory (too many to list, really), only some of which are stringy in nature.
And there’s a bunch of really interesting formal work in Lattice Gauge Theory (though, I gather, some of those people have a hard time getting jobs).
This is all off the top of my head. And, as free advice proferred over the internet, worth every penny you paid for it.
amused,
I think Jacques is giving you the same, honest answer to your question
” It looks like most of such groups are focussing on string theory, branes etc. Would they be at all interested in applications from people working on other formal theory topics?”
that you would get from just about any faculty member in any such group:
No way.
A couple years ago I tried to quantify the dominance of string theorists in US particle theory groups at elite universities. Going through the list of faculty at the highest-ranked half dozen US universities (according to US News and World Report: Berkeley, Caltech, Harvard, MIT, Princeton (including IAS) and Stanford) I found 22 particle theorists with tenure who had post-1981 Ph.Ds. Of these 18 were string theorists, 2 did brane-worlds (and don’t seem to object to being identified in the media as string theorists), one was an MSSM phenomenologist, and one did high-temperature QCD. Not a non-phenomenologist non-string theorist in the bunch. Zero. I’d be curious if anyone has more up to date data, or a wider sample size. Lee Smolin has analogous data for how often US universities have been willing to hire non-string theorist people in quantum gravity.
Dear Peter,
You wrote:
My “below the belt” comment was in reference to your assertion that I was merely “complain[ing] about the fact that [you]’ve chosen to say something [I] don’t want to hear.” As I read that, you were essentially accusing me of sticking my head in the sand about challenges to my research field, which is a pretty nasty insult to a scientist (and, of course, untrue).
I have been open about the fact that I haven’t read your book, and I recognize that without having done so I am very limited in the sort of comments I can reasonably make about it. If you look back at what I’ve written, you will see that I have said nothing about the detailed content of your book (or Prof. Smolin’s, for that matter). My concerns have been entirely about the general notion of a popular science book that puts a substantial fraction of its focus on debunking (or attempting to debunk) a current research area. The fact that you happen to have written such a book and that its target happens to be my own field is almost beside the point in discussing the general issue (though they were clearly involved in drawing my attention to it).
If that is not an accurate description of your book on a very general level, then I do apologize for leaping to conclusions. But the title (Not Even Wrong, your usual take on string theory as science) and half of the subtitle (“The Failure of String Theory”) certainly give the impression that one major focus of the book is problems with string theory. And the description of the book on Amazon.com only describes it as a criticism of string theory: if that topic does not comprise a substantial fraction of the text, you might want to ask them modify their summary.
I do appreciate your comments on the actual audience for your book: you make a good point that such an audience is looking to learn more details, not to be talked into enjoying science in the first place. I’m still not convinced that a public anti-string-theory campaign is the ideal approach (if nothing else, it feels like you’re still allowing the string theorists to define the debate), but you’ve explained why you couldn’t see any better option from your point of view, and I can respect that.
I’d like to think that I personally have been innocent of all of the things that you say you’d like to see string theorists stop doing. From where I sit inside the field, it’s hard to imagine any string theorists that I know being truly guilty of any of them (most of the folks I work with are skeptical of anthropic arguments as well), but I am willing to believe you that there are some people out there who have done so, and I can see how frustrating that would be. I hope you’ll be careful not to lump all of us together as collectively guilty for the misbehavior of a few.
Thanks again for taking the time to answer my questions!